1. Field of the Invention
This invention relates to a process for producing meta-aminobenzotrifluoride.
2. Description of Prior Art
Meta-aminobenzotrifluoride (also known as 3-trifluoromethylaniline or MABTF) is a chemical intermediate to dyes, germicides, pharmaceuticals and crop protection chemicals.
The standard manufacturing route for making MABTF involves the steps of (1) nitration of trifluoromethylbenzene with a nitration agent to form meta-nitrobenzotrifluoride followed by (2) reduction of this intermediate to MABTF by catalytic hydrogenation. See M. M. Boudakian "Fluorinated Aromatic Compounds" Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 10, 3rd Edition, pp. 919 and 923. The reduction step may also be carried out using iron filings, HCl and H.sub.2 to give MABTF in 74-85% yield. See A. E. Porai-Koshits et al., J. Applied Chem. (USSR), 28, p. 921 (1955). However, during the nitration step, the corresponding ortho and para-isomers are also made. See Manufacturing Chemist & Aerosol News, January 1970 pp. 37-41. Separation of these unwanted isomers before or after the reduction step is costly and lowers the overall yield of MABTF based on the original starting materials. Furthermore, this route involves multiple handling steps which also raise the cost of the process.
Separately, U.S. Pat. No. 4,393,257 (Nakagawa et al.) teaches that m-nitrobenzotrichloride may be fluorinated with anhydrous HF in a gaseous phase at elevated temperatures and in the presence of Cl.sub.2 to obtain primarily meta-nitrobenzotrifluoride. This reference does not suggest that a simultaneous reduction reaction may also occur to form MABTF.
One objective of the present invention is to provide a process for making meta-aminobenzotrifluoride in high purity.
Another objective of the present invention is to provide a process for the simultaneous fluorination-reduction of meta-nitrobenzotrichloride to meta-aminobenzotrifluoride.
Still another objective of the present invention is to provide a process for the high-yield single reactor fluorination-reduction reaction of meta-nitrobenzotrichloride to meta-aminobenzotrifluoride.